Dyeing of polyacrylonitrile textile materials with cationic dyes in the presence of aromatic esters

ABSTRACT

ESTERS OF THE MONOCARBOXYLIC AND/OR DICARBOXYLIC AROMATIC ACIDS AND DERIVATIVES THEREOF ARE USED AS LEVELING AGENTS IN THE DYEING OF POLYACRYLONITRILE-CONTAINING MATERIALS WITH CATIONIC DYES. LEVEL DYEING OF POLYACRYLONITRILE MOIETIES ARE ACHIEVED WITHOUT LOSS OF COLOR YIELDS OR BULKING EFFECTS.

United States Patent Int. Cl. D0611 5/04 US. Cl. 8-173 25 ClaimsABSTRACT OF THE DISCLOSURE Esters of the monocarboxylic and/ ordicarboxylic aromatic acids and derivatives thereof are used as levelingagents in the dyeing of polyacrylonitrile-containing materials withcationic dyes. Level dyeing of polyacrylonitrile moieties are achievedwithout loss of color yields or bulking effects.

BACKGROUND OF THE INVENTION This invention relates in general to aprocess for dyeing polyacrylonitrile materials, and more specifically,to a process for level dyeing polyacrylonitrile materials with basic orcationic dyestuffs.

Polyacrylonitrile materials may be in the form of fibers, fabrics orshaped articles. This invention applies to all forms ofpolyacrylonitrile materials derived from acrylonitrile polymers andcopolymers containing 85% or less acrylonitrile units in the moleculeand to all such materials which are modified with adjuvants which provide anionic dye sites as acceptors for cationic dyestuffs. It alsoapplies to the dyeing of polyacrylonitrile which is blended with othersynthetic or natural substances. For the sake of brevity the termacrylic is used to designate the polyacrylonitrile substances undergoingtreatment with dyestuffs.

Acrylic fibers have such a strong affinity for basic dyestuffs that thedyes, which become absorbed on the dye sites, do not distributethemselves uniformly under atmospheric dyeing conditions at the boil.This results in uneven or unlevel dyeing. In the dyeing of acrylics, theafiinity of each dye and the rate of exhaustion of dyestuffs from thedyebath vary with the dye being used often making the levelness ofdyeing unpredictable. Temperature difference from one part of the dyeingequip ment to the other aggravates this difficulty. Certain chemicaladditives and methods have been used to overcome these difiicultie to acertain extent, but there are still deficiencies in performance,handling and cost which make them unacceptable for routine dyeing.

One method used to prevent uneven or unlevel dyeing of acrylic fibers isknown as the anionic retarder system. In the anionic retarder system ofdyeing with cationic dyestuffs, an anionic precipitant or complexingagent such as the sodium salt of sulfonated dinaphthyl methane isemployed. This additive forms a complex which is dispersed in thedyebath together with a non-ionic surfactant to keep the bath in asuitable state of colloidal dispersion. At temperatures below boilingthe complex bonds very loosely with the acrylic fiber and some migrationor leveling of the dye occurs on the surface of the fiber. As thetemperature of the dyebath is raised, this complex breaks down andallows the dyestuff to diffuse into the fiber. The anionic retarderremains active in the dyebath. While this method is useful in promotingleveling, it causes a very great reduction in color yield and loss ofdyestuff which is retained in the dyebath. The dyes do not penetrate thematerial well and in some instances the incompatabiliice ties ofcationic dye and anionic agent are too great to be economically overcomeby means of a non-ionic additive.

Another method used to prevent unlevel or uneven dyeing is known as thecationic retarder system of dyeing. In this system a cationic agent isemployed at the start of the dyeing. Cationic retarders are generallywater-soluble organic substances which decrease the rate of exhaustionof the cationic dyestuffs. In effect they act as competitive colorlessdyestuffs which block dye sites and generally lack migrating abilitythemselves. Even with these cationic retarders the dyestuffs strike orexhaust at different rates so that fast striking dyes exhaust rapidly atthe higher temperatures and slow striking dyes do so slowly. Cationicretarders cause a reduction in color yield although not as great as theanionic retarders and are difiicult to remove from the materialundergoing treat ment with dyestuffs. When acrylics of a light or pastelshade are desired, it is necessary to use high concentrations ofcationic retarder. Since cationic retarders are difficult to remove fromthe acrylics, it is necessary to use large amounts of dyestuff tosubsequently overdye the light or pastel acrylics, for example, tochange an acrylic fabric from a light blue shade to a navy blue.Accordingly, in overdyeing the pastel colored acrylics, it is necessaryto use a higher concentration of the dyestuff than when thepastel-colored acrylic has been dyed in the absence of the retarder.

In certain types of dyeing of acrylic fibers and yarns e.g., those usedin sweaters and carpeting, it is desirable to obtain a high bulk effect.Bulking is achieved by allowing the fiber to shrink in the boilingdye-bath. Cationic retarders greatly reduce bulking.

Non-surface active cationic leveling agents such asbenzyltrimethylammonium chloride and benzylpyridiurn chloride, are oftenused in place of cationic retarders. These agents have greater mobilitythan retarders, however, they cause losses in dyestutf yields.

All of the conventional methods of dye leveling are characterized bysensitivity to overdoses of the leveling agent. Excessive amounts oreven small quantities above the optimum of the cationic retarders,anionic retarders and non-surface active cationic leveling agents citedabove can greatly prolong dyeing time, reduce color yields, decreasebulking and fail to improve the levelness of the dyeing for which theyare intended.

OBJECTS OF THE INVENTION Accordingly, it is an object of this inventionto provide a process for the level dyeing of polyacrylonitrile materialsby means of basic or cationic dyestuffs.

It is another object of this invention to provide a process for thelevel dyeing of polyacrylonitrile materials wherein diiferent dyes usedin the process produce minimum variation in dye aflinities and rate ofexhaustion of dyestuffs from the dyebath.

It is still another object of this invention to provide a process forthe dyeing of polyacrylonitrile materials wherein temperaturedifferences between various parts of the dyeing equipment do not produceunlevel and uneven dyeing.

Another object of this invention is to provide an economic process forthe dyeing of polyacrylonitrile materials. wherein there is excellentdye pentration and little or no reduction in color yield due to thepromotion of dye leveling in the material.

Still another object of this invention is to provide a process for thelevel dyeing of polyacrylonitrile materials wherein the agents used topromote the leveling are easily removed from the material undergoingtreatment with dyes and do not inhibit subsequent overdyeing.

Still another object of this invention is to provide a process fordyeing acrylics wherein a high bulk elfect is retained when agentspromoting leveling of the dye are added to the dye bath.

Another object of this invention is to provide a process for leveldyeing of acrylics wherein excessive amounts of the leveling agent willnot have adverse effects on dyeing time, color reduction, bulking andlevelness.

SUMMARY OF THE INVENTION We have found that these and other objects areaccomplished by the addition of lower alkyl esters of monocarboxylic anddicarboxylic acid derivatives of aromatic compounds in a dyebathcontaining at least one cationic dye. This class of esters willhereinafter be referred to as aromatic esters. The aromatic esters ofthis invention may be advantageously applied with emulsifiers in orderto get be reasonably uniform dispersion of the aromatic esters in thedyebath. However, level dyeing is obtained even in the absence of theemulsifier.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The aromatic esters which arepreferred as additives to induce level dyeing of acrylic materials, arethose selected from the group having the following structural formula:

(COOR), (C1): -d

where R is a lower alkyl of C to C when a is 2 and C 'to C when a is l;b is 0 or 1 and 0 when a is 2; c is 0, 1 or 2; d is O or 1 and 0 when ais 2. Examples of lower alkyl radicals are methyl, ethyl, propyl,isopropyl, and butyl. In general the aromatic moiety includes benzene,halogen substituted benzene, hydroxybenzene (phenol) and lower alkylderivatives of benzene. Examples of these aromatic esters are the methylester of monochlorobenzoic acid, the methyl ester of dichlorobenzoicacid, butyl benzoate, methyl salicylate, methyl cresotinates, methyltoluates, dimethyl orthophthalate, dimethyl meta-phthalate, dimethylparaphthalate, the isopropyl esters of ortho-, meta-, and para-phthalicacid and the like. Combinations and mixtures of the aromatic esters mayalso be utilized in level dyeing. Concentration of the aromatic estersis not critical. It is only necessary to have an effective amount of thearomatic ester. We have found that as little as 0.4% on the weight ofthe acrylic material being dyed is an effective amount. Concentrationsof or higher of the aromatic ester (based on the weight of the acrylic)produce fully satisfactory performance. However, concentrations of thearomatic ester in excess of 20% are generally not required to producethe desired leveling effect. Good results are obtained when theconcentration of aromatic ester is between 1% and 6% (based on theweight of the acrylic). The preferred concentration provides adequateleveling at reasonable cost.

Since the aromatic esters of this invention are at most slightly solublein the dyebath, they are usually applied with a suspending agent oremulsifier in order to provide a uniform dispersion of the aromaticester at the start of the dyeing. The emulsifiers useful for suspensionof the aromatic esters in the dyebath are preferably the non-ionic type.However, small quantities of anionic or cationic emulsifiers may beincluded therein. A typical emulsifier is a mixture of ethoxylatednonylphenol, diisopropylphosphate and monoethanolamine in 33%isopropanol in Water. Emulsifiers may be used in effective amounts, thatis, there may be more emulsifier added to the composition than aromaticester, or there may be less emulsifier than aromatic ester. In fact wehave found that leveling of the dye may be accomplished with noemulsifiers in the dye bath.

It is preferred that the-aromatic ester be added to the dyebath at thestart of the dyeing. However, effective level dyeing is possible even ifaddition of the aromatic ester and emulsifier are made subsequent to thestart of the dyeing.

Other chemicals are ordinarily employed in the dyeing of acrylicmaterials. For example, acetic acid and sodium acetate are used asbuffers to mtaintain pH control of 4.5 to 5.5 which is generally theoptimum pH for most cationic dyes. Sodium sulfate is used forstabilizing the shade of many dyes against pH variations. It is deemedthat other chemicals and techniques may be used in the practice of thisinvention by one skilled in the art of dyeing.

The following examples are set forth to illustrate more clearly theprinciples and practice of the invention to those skilled in the art. Inthe examples given below all chemical concentrations are expressed aspercent of acryl ic (fiber or fabric) weight.

The following aromatic ester-emulsifier compositions were prepared inaccordance with this invention and are used in examples set forth below:

COMPOSITION A 55 parts dimethyl phthalate 45 parts emulsifiedcomprising:

24 parts ethoxylated nonylphenol 4 parts diisopropylphosphate 2 partsmonoethanolamine 15 parts 33% isopropanol in water COMPOSITION B 55parts diethyl phthalate 45 parts emulsifier as in Composition ACOMPOSITION C 55 parts butyl benzoate 45 parts emulsifier as inComposition A COMPOSITION D 55 parts methyl-p-toluate 45 partsemulsifier as in Composition A COMPOSITION E 55 parts methyl benzoate 45parts emulsifier as in Composition A COMPOSITION F 55 parts methylsalicylate 45 parts emulsifier as in Composition A COMPOSITION G 55parts methyl-o-cresotinate 45 parts emulsifier as in Composition ACOMPOSITION H 77 parts dimethyl phthalate 23 parts emulsifier as inComposition A Example 1 Comparative evaluation of leveling performancewas made in a Launder-O-Meter by migration experiments using equalweights of undyed acrylic fabric and fabric dyed with cationic dyestuff,2% Basic Red 22. A liquor ratio of 10 parts to 1 part total fabricweight was used. Each bath contained (based on total fabric weight) 10%anhydrous sodium sulfate, 0.5% sodium acetate and acetic acid to adjustthe bath pH to 4.5. The following additives were incorporated intoseparate Launder-O- Meter pots: (a) none; (b) 4% of 60%benzyltrimethylammonium chloride solution; (c) 4% of 30%lauryltrimethyl-ammonium chloride solution, a conventional cationicretarder; (d) 2.8% Composition H and (e) 2.2% dimethyl phthalate. Thepots were sealed, fastened in the Launder-O-Meter and then heated to theboil. Agitation and heating were maintained for one and a half hours.After cooling, the fabrics were rinsed and evaluated for dyestufftransfer from dyed to undyed material. The fabrics treated with 2.8% ofComposition H and 2.2% dimethyl phthalate showed the greatest amount ofdyestuff transfer from dyed to undyed fabric and were essentiallyequivalent. The control (a), (b) and (0) were less effective. Theexperiment was repeated using fabrics dyed with 2% Basic Blue 3 Cl.51005 and 2% Basic Green 4 CI. 42000. Similar results were obtained.

Example 2 Comparative evaluations of leveling performance were conductedwith each of the following additives:

(a) 4% of a 60% solution of benzyltrimethylammonium chloride (b) 4% ofComposition A (c) 4% of Composition B (d) 4% of Composition C Tests wereconducted as in Example lat a liquor to fabric ratio of 25:1 instead of:1 using acrylic fabrics dyed with 1% Basic Orange 25 and 1% Basic Blue3.

In each case, that is, those dyed with 1% Basic Orange 25 and those dyedwith 1% Basic Blue 3, more dyestuflt was transferred with CompositionsA, B and C than with the solution of benzyltrimethylammonium chloride.

Example 3 Comparative laboratory beaker dyeings were carried out at aliquor ratio of :1 on an acrylic yarn using a dye combination of 0.1% DuPont Severon Blue EG and 0.05% Basic Yellow 21. With 3% Composition Hagainst a control and incorporating acetic acid, sodium acetate andsodium sulfate in each beaker as in Example 1, dyeing with Composition Hproduced well penetrated dye with superior lightfastness and equalbulking of the yarn. Similar results were obtained when the dyestuffconcentrations were increased five fold.

Example 4 Example 3 was repeated using a very heavy dyestutf combinationof 3.5% Geigy Maxilon Red 3BL and 1.5% Maxilon Red GRL. Approximately15% greater exhaustion of dyestuffs and yield of color were obtainedwith 3% Composition H as compared to the control.

Example 5 Comparative simultaneous dyeings were made in an AhibaVistamatic automatic dyeing machine on an acrylic fabric at a liquor tofabric ratio of :1 using a combination of 0.5% Basic Yellow 13 and 1%Basic Blue 77. Each dye bath contained 10% sodium sulfate, 0.5% sodiumacetate and acetic acid to maintain pH at 4.5 plus 4% of one of thefollowing additives:

#1 60% solution of benzyltrimethylammonium chloride #2 solution oflauryltrimethylmammonium chloride #3 Equal parts of sodiumdisulfonaphthylmethane and ethoxylated tallow alcohol (anionic retardersystem) #4 Composition A #5 Composition B #6 Composition C #7Comoposition D #8 Comoposition E #9 Composition F #10 Composition G #11None (control) The temperature of the dyebaths was raised at the rate ofapproximately 1 F. per minute to the boil and then maintained at theboil for one and a half hours. As the temperature was raised the machinewas stopped periodically to remove small swatches of the separatefabrics to observe the rate of dye exhaustion. The dye bathincorporating additive #2, typical of the cationic retarder system,showed very little dye exhaustion even up to the boil. Additive #1showed only slight retardation. Additive #3, typical of the anionicretarder system, showed very slight retardation, but when the boil wasreached there was a very great deal less exhaustion and compared to thecontrol the final dyeing showed a loss of about 35% dyestufii, whileadditives #1 and #2 showed about 10% and 15% loss respectively.Additives #4-#10, illustrative of this invention caused excellentpenetration of the dye and equality in color yield when compared withthe control. p

In accordance with the above examples, the objects of this inventionhave been carried out. Acrylonitrile polymers have been subjected todyeing with cationic dyestutfs by means of a process which causedsuperior lightfas'tness and uniform and level penetration of the acrylicmaterial with dye. The process of this invention increased exhaustion ofthe dyestufi from the dye bath, that is, caused the acrylic material toincorporate greater amounts of dye resulting in less dyestulf retainedin the used dye bath. Acrylic yarns subjected to dyeing in accordancewith the process of this invention showed equal bulking throughout.

The above examples are not meant to limit the scope of the invention orthe applications to which this invention may be directed. It is to beunderstood that although the invention has been described with specificreference to particular embodiments thereof, it is not to be so limited,since changes and alterations therein may be made which are in the fullintended scope of this invention as defined by the appended claims.

We claim:

1. A process for level dyeing acrylonitrile polymer textile materialswith a cationic dye comprising adding at least one aromatic ester havinga structural formula:

(000R). M s)a where R is a lower alkyl radical and a is 1-2; b is 0-1and 0 when a is 2; c is 0-2; d is 0-1 and 0 when a is 2, to an acid dyebath containing at least one cationic dye; adding the acrylonitrilepolymer to said dye bath; heating said dye bath; and removing saidacrylonitrile polymer from said dye bath.

2. A process in accordance with claim 1 wherein the lower alkyl radicalis one to four carbon atoms when a is 2 and one to eight carbon atomswhen a is 1.

3. A process in accordance with claim 1 wherein the lower alkyl radicalis selected from the group consisting of methyl, ethyl, propyl,isopropyl and butyl.

4. A process in accordance with claim 1 wherein the aromatic ester isdimethyl phthalate.

5. A process in accordance with claim 1 wherein the aromatic ester isdiethyl phthalate.

6. A process in accordance with claim 1 wherein the aromatic ester isbutyl benzoate.

7. A process in accordance with claim 1 wherein the aromatic ester ismethyl-p-toluate.

8. A process in accordance with claim 1 wherein the aromatic ester ismethyl benzoate.

9. A process in accordance with claim 1 wherein the aromatic ester ismethyl salicylate.

10. A process in accordance with claim 1 wherein the aromatic ester ismethyl-o-cresotinate.

'11. A process in accordance with claim 1 wherein the concentration ofthe aromatic ester is at least 0.4% based on the weight of the materialto be dyed.

12. A process in accordance with claim 1 wherein the concentration ofthe aromatic ester is from 1% to 6% based on the weight of the materialto be dyed and the pH of the dye bath is about 4.5 to 5.5.

13. The process of claim 1 wherein the acrylonitrile polymer is a fiber.

14. The process of claim 1 wherein the acrylonitrile polymer is afabric.

15. The process of claim 1 further comprising adding a non-ionicemulsifier to the dye bath to suspend the dye bath insoluble aromaticester.

'16. The process of claim 15 wherein the non-ionic emulsifier comprisesminor quantities of anionic emulsifier.

17. The process of claim '15 wherein the non-ionic emulsifier comprisesminor quantities of cationic emulsifier.

18. A dye bath composition for dyeing acrylonitrile polymer textilematerials with cationic dye consisting of:

(a) a fluid medium;

(b) at least one cationic dye;

(c) at least one aromatic ester having a structural formula:

(000R). HM D i -sh where R is a lower alkyl radical and a'is 1-2; b is0-1 and 0 when a is 2; c is 0-2; d is 0-1 and 0 when a is 2; and

(d) an acid to adjust the pH of said fluid medium. 19'. The compositionof claim 18 wherein the lower alkyl radical is one to four carbon atomswhen a is 2 and one to eight carbon atoms when a is 1.

20. The composition of claim 13 wherein the lower alkyl radical isselected from the group consisting of methyl, ethyl, propyl, isopropyland butyl.

21. The composition of claim 18 wherein the concentration of thearomatic ester is at least 0.4% based on the weight of the material tobe dyed.

22. The composition of claim 18 wherein the con centration of thearomatic ester is from 1% to 6% based on the weight of the material tobe dyed and said acid to adjust the pH of said fluid medium is aceticacid.

23'.- The composition of claim 18 further consisting of an effectiveamount of at least one non-ionic emulsifier.

24. The composition of claim 23 wherein the ratio of emulsifier toaromatic ester is 1: 1.2 to 1:3.4.

25. The composition of claim 23 wherein the concentration of theemulsifier and the aromatic ester is at least 0.4% based on the weightof the acrylonitrile polymer.

References Cited UNITED STATES PATENTS 3,124,412 3/ 1964 Fidel! et al8-177 AB X 2,362,377 11/ 1944 Heymann 8-173X 23 94,689 2/1946 Heymann8173 X OTHER REFERENCES I. E. Lynn et al., Advances in TextileProcessing, vol. 1, 196-1, pp. 362-363, Textile Book Publishers Inc.,New York, N.Y., 8-173 Lit.

GEORGE F. LESMES, Primary Examiner T. I. HERBERT, 1a., AssistantExaminer US. Cl. X.R. 8-177 AB

